(1) Field of the Invention
The present invention relates to an actuating device, particularly to an actuator suitably used for an air conditioner in a vehicle.
(2) Related Art Statement
Heretofore, the air conditioner for controlling the temperature of a vehicle compartment, for example, is assembled with an air-mixing door for adjusting a mixed amount of cooled air and warmed air as well as an actuator for driving the air-mixing door.
The actuator comprises an upper housing member and a lower housing member. In the lower housing member, there are arranged a driving source, a circuit board for controlling operation of the driving source, a power-transmission mechanism for transmitting driving power of the driving source to an output shaft to which an air-mixing door is attached, a connector to which electric wires from the driving source are connected, a power input connector to which electric wires from a vehicle body are connected, etc.
When the actuator is to be assembled, the driving source, the power-transmitting mechanism and the connectors are arranged inside the lower housing member, and the circuit board is assembled into the lower housing member by soldering the terminals of the connectors to respective connection terminals of the circuit board. Then, the upper housing member is attached to the lower housing member.
When the terminals of the connectors are to be soldered to the respective connection terminals of the circuit board, an insulating flux is used as an auxiliary agent for facilitating the soldering work and assuredly fixing the solder to the circuit board. See JP-A 5-95177 (Page 2, FIG. 1), for example.
However, when the terminals of the connectors are soldered to the respective connection terminals of the circuit board in the state that the circuit board is arranged inside the lower housing member, it is likely that solder balls and insulating flux scattering during soldering come in the lower housing member, because the circuit board is arranged inside the lower housing member without being isolated therein.
When the actuator is assembled in the state that the solder balls are present inside the lower housing member, the balls may be caught by driving portions of the power-transmitting mechanism, etc., resulting in operational disorder.
Further, if the scattered insulating flux attaches to a conductive portion of such as the connector, the flux-attached conductive portion becomes insulated, which may cause insufficient electric contact.
In order to prevent invasion of the solder balls into the lower housing member and attachment of the flux to the conductive portion, it is a conventional practice that a invasion-preventing cover is placed over the driving source, the power-transmitting mechanisms, etc. arranged in the lower housing member during soldering or the circuit board is cleaned after soldering so as to remove excess solder remaining on the circuit board. According to these techniques, the number of steps increases and thus the production cost rises, although it is possible to prevent the operational disorder due to the solder balls being caught by the driving portion of the power-transmission mechanism, etc. and the insufficient electrical contact due to the attachment of the flux.